1. Field of the Invention
This invention relates to an information signal reproducing apparatus and more particularly to an apparatus provided with means for detecting a distance or pitch between recording tracks which are formed, one after another, on a record bearing medium in a direction intersecting the moving direction of the record bearing medium.
2. Description of the Prior Art
With regard to the apparatus of the above-stated kind, there have been known magnetic recording/reproducing apparatus (hereinafter called VTR's) which record with a rotary head a video signal on a magnetic tape forming recording tracks obliquely thereon, one after another, with one field portion of the video signal thus recorded in each of the tracks. These known VTR's include a type in which the distance between recording tracks (hereinafter referred to as the track pitch or TP for short) is determined by selecting a tape moving speed in carrying out recording on the tape. In reproducing the recorded video signal, the track pitch is detected and a tape moving speed and a head to be used are automatically determined, ensuring satisfactory reproduction. In this specification, the invention is described with VTR's of this type used as examples.
Heretofore, a VTR of this type has been arranged such that: In carrying out a recording operation, a tracking control signal is recorded in the direction of the moving tape in relation to recording tracks formed at the end of the tape or in relation to a recording video signal. In carrying out a reproducing operation, this control signal is reproduced to find the frequency thereof. The tape moving speed employed for recording, or the TP, is detected from the frequency. A reproducing head and a tape moving speed are controlled based on the result of detection, automatically ensuring satisfactory reproduction.
Meanwhile, as a result of a recent tendency to reduce the size of VTR's and to increase recording density, there have been proposed VTR's of the type in which pilot signals for tracking control are recorded in the video signal recording tracks by superimposing them on the video signal instead of recording the above control signal. Generally, in this type of VTR, a plurality of pilot signals of different kinds are superimposed on each of the recording tracks, one after another. A tracking control signal for reproduction is obtained by detecting a level difference between the cross-talk components of the pilot signals obtained from adjacent recording tracks during reproduction. Furthermore, during recent years, there have been proposed VTR's of the type in which a rotary head is mounted on an electric-mechanical conversion element or a piezoelectric element such as a bimorph element. The head is shifted in a direction perpendicular to the rotating direction thereof in such a manner that the recording tracks can be accurately traced by the head even in the event of a varied speed reproducing operation such as slow motion reproduction, high speed searching reproduction, etc. The VTR of that type is capable of giving a reproduced picture of excellent quality since, unlike the conventional VTR's of other types, no noise bar arises even during varied speed reproduction. A shortcoming of the VTR of that type, however, lies in that the head shifting means, such as the above-stated electric-to-mechanical conversion element or the like, must be controlled by means of a control signal based on the reproduction speed and the TP.
While the VTR using the above-stated pilot signals for tracking control permits an increase in recording density, the absence of the control signal mentioned in the foregoing deprives the VTR of any signal that is directly repressentative of the TP. The TP is, thus, not automatically detected and the tape speed employable for recording, or the TP, has been limited in general to one value.
In the VTR which is capable of carrying out the above varied speed reproduction on the other hand, the control signal must be varied with the TP. Therefore, in cases where varied TP values are to be used for recording, the VTR necessitates the provision of many different control signals. Generally, the slant or inclination of the control signal is in proportion to the number of recording tracks to be crossed by the head during one field period. In order to obtain this slant, a so-called still pattern signal, having a slant which causes the head shifting means to be shifted the extent of one TP during one field period, is subtracted from a signal having a slant corresponding to the tape moving speed. This still pattern signal varies with the TP. Therefore, in order to obtain a control signal for the head shifting means, a VTR having a plurality of different TP values necessitates an arrangement for preparing still pattern signals by counting the outputs of an oscillator having a plurality of oscillating frequency values corresponding to the recording TP values.
It is an object of the present invention to provide an information signal reproducing apparatus which is capable of eliminating the shortcomings of the prior art apparatus mentioned in the foregoing and which is arranged so that the distance or pitch between recording tracks is detectable even where there is no signal indicating the distance between the recording tracks.
It is another object of the invention to provide an information signal reproducing apparatus which is capable of producing a good reproduced information signal by accurately detecting the distance between recording tracks.
It is a further object of the invention to provide an information signal reproducing apparatus which is always capable of producing a good reproduced information signal regardless of the distance between the recording tracks and the travelling speed of a record bearing medium.
These and further objects and features of the invention will become apparent from the following detailed description of preferred embodiments thereof taken in conjunction with the accompanying drawings.